Flagyl ER (Metronidazole) Extended-Release Tablets: Pack Sizes and Prices

We list Flagyl ER, the extended-release oral tablet form of metronidazole, in two strengths, 200 mg and 400 mg, with several pack sizes for each. Because the active ingredient, release type, and route stay the same across every option, the real choice we offer is about the prescribed strength, quantity, and total value rather than about the medicine itself. This guide walks through the pack sizes we currently offer, how their unit value compares, and how expected use, storage, and expiry should shape the option you choose.

Our current price and choice overview

Flagyl ER tablets are taken by mouth and release metronidazole over an extended period, which is different from standard immediate-release metronidazole tablets even though the active ingredient is identical. We offer 200 mg tablets in packs of 120, 180, 270, or 360, and 400 mg tablets in packs of 90, 120, 180, 270, or 360. Every pack is priced in Australian dollars. The exact current price, unit value, and any pack-specific saving are shown through our offer and comparison rather than fixed in running text, so the figures remain aligned with the option available at checkout.

Flagyl ER 400 mg package prices and unit value

Comparing packs by price per tablet is a practical way to assess value, but it should be considered alongside the prescribed course, the amount that will genuinely be used, suitable storage, and the printed expiry date. A larger pack may have a lower average unit price, but it is not better value if it leaves an unnecessary supply or encourages treatment beyond a prescriber's directions.

The comparison above sets out the exact quantities, current prices, price per tablet, and relative saving for each 400 mg pack size we offer. It is specific to the 400 mg strength and should not be used to infer the price or savings for 200 mg packs; the current 200 mg options are shown when that strength is selected. Check the pack quantity against the prescribed treatment plan before completing checkout.

When comparing package value, consider:

• whether the strength exactly matches the prescription;
• how many tablets the planned course requires;
• whether the pack can be used before its printed expiry date;
• whether appropriate storage at home is available; and
• the total pack price as well as the price per tablet.

How do you choose between Flagyl ER 200 mg and 400 mg tablets?

Strength and quantity are separate decisions. Use the strength and number of tablets stated by the prescriber rather than trying to recreate a dose by substituting a different strength. Extended-release tablets should not be split, crushed, or combined in a self-calculated regimen unless a prescriber or pharmacist has specifically confirmed the instructions.

The table below sets out the pack sizes we currently offer for each strength:

A few practical points help when choosing between these options:

• Match the strength on the product option and pack label to the strength prescribed.
• Check the required tablet count rather than rounding up solely because a larger pack has a lower unit price.
• If the smallest available pack contains more tablets than the prescribed course requires, ask a pharmacist how to manage and dispose of the remainder safely.
• Do not keep leftover antibiotic tablets for an unplanned future infection or share them with another person.
• Confirm the selected strength and quantity in our checkout before paying.

Flagyl ER, immediate-release metronidazole, Tinidazole, and Secnidazole

Flagyl ER is the extended-release branded presentation of metronidazole. It is distinct from standard immediate-release metronidazole tablets, which release the active ingredient differently and may follow a different dosing schedule. The formulations should not be treated as automatically interchangeable, even when the active ingredient is the same.

We list Flagyl ER specifically for customers directed to use the extended-release form. For infections where a prescriber has selected a different nitroimidazole, we also carry Tinidazole and Secnidazole. These medicines belong to the same broad drug class but differ in approved uses, dosing schedules, pharmacokinetics, and suitability. They are alternatives only when selected by a prescriber, not direct substitutes to choose solely by pack price.

Established use and the role of Flagyl ER

Metronidazole is a nitroimidazole antimicrobial with a long-established role against susceptible anaerobic bacteria and certain protozoal organisms. Its recognised uses include:

• bacterial vaginosis in adult women, which is the established indication for the extended-release tablet formulation;
• anaerobic bacterial infections affecting the abdomen, pelvis, skin, and other tissues when an appropriate metronidazole formulation is prescribed; and
• protozoal infections such as giardiasis, amoebiasis, and trichomoniasis, which are generally treated with immediate-release regimens rather than assuming that the extended-release form is suitable.

The infecting organism, site of infection, formulation, and treatment schedule all matter. Flagyl ER should therefore be used for the condition and course directed by a prescriber rather than as a general-purpose antibiotic. It does not treat viral infections, and its activity against anaerobic organisms does not make it suitable for every bacterial infection.

How does Flagyl ER work and how should it be taken?

Metronidazole enters susceptible anaerobic bacteria and protozoa, where it is converted into reactive compounds that damage microbial DNA and disrupt its structure, leading to cell death. This activation occurs most effectively in susceptible anaerobic organisms and certain protozoa, which is why metronidazole does not provide reliable coverage for typical aerobic bacteria.

The extended-release tablet is generally taken once daily on an empty stomach, at least one hour before or two hours after food. Follow the exact directions provided for the prescribed product and course. Swallow the tablet whole rather than crushing, chewing, or splitting it, as damaging an extended-release tablet can alter how the medicine is released.

Take doses at about the same time each day. If a dose is missed, follow the medicine instructions or ask a pharmacist; do not take two doses together to compensate unless specifically directed. Symptoms may begin to improve during the first few days, but the course should normally be completed as prescribed even if the person feels better earlier. Seek medical review if symptoms worsen, fail to improve, or return after treatment.

Important safety information and interactions

Metronidazole has a well-established safety profile when used as directed, alongside important contraindications, interactions, and precautions. Individual advice is especially important for people with liver disease, neurological disorders, blood disorders, or a history of reactions to nitroimidazoles.

Common effects to expect

• A metallic or bitter taste, nausea, reduced appetite, abdominal discomfort, diarrhoea, or other gastrointestinal upset.
• Headache or dizziness in some patients.
• Darkened urine, which is a known effect of metronidazole metabolites and is usually harmless.

Interactions and precautions

• Avoid alcohol and products containing alcohol or propylene glycol during treatment and for at least three days after the final dose because unpleasant reactions such as flushing, nausea, vomiting, headache, or palpitations may occur.
• Metronidazole can increase the anticoagulant effect of warfarin and other vitamin K antagonists. Clotting tests and dose adjustment may be needed under professional supervision.
• Do not combine metronidazole with disulfiram or use it within two weeks after disulfiram because confusion or other psychotic reactions may occur.
• Caution applies with lithium, phenytoin, phenobarbital, busulfan, ciclosporin, fluorouracil, and cimetidine because clinically important changes in medicine levels or effects can occur.
• Use during pregnancy should be based on a prescriber's assessment of benefit and risk. Metronidazole passes into breast milk, so breastfeeding advice should be obtained before treatment and breastfeeding is generally avoided or interrupted when directed during a course.
• The extended-release tablet is established for adult use. Paediatric doses used with immediate-release metronidazole should not be transferred to this formulation.
• Dizziness, confusion, hallucinations, seizures, poor coordination, numbness, or visual disturbance can occur. Do not drive or operate machinery if affected, and obtain prompt medical advice for neurological symptoms.

Anyone with known hypersensitivity to metronidazole, another nitroimidazole, or a formulation ingredient should not take Flagyl ER. Severe rash, facial swelling, breathing difficulty, persistent vomiting, jaundice, severe abdominal pain, seizures, or new tingling or numbness requires urgent medical assessment.

For prolonged or repeated treatment, a prescriber may monitor blood counts, liver function, treatment response, and signs of peripheral neuropathy or other neurological effects. This is particularly important when treatment extends beyond a short course or when significant liver impairment could reduce metronidazole clearance.

Do you need a prescription to order Flagyl ER in Australia?

Oral metronidazole is classified as a Schedule 4 Prescription Only Medicine in Australia. Metronidazole tablet products are included in the Australian Register of Therapeutic Goods, and 200 mg and 400 mg tablet listings also appear on the PBS. Eligibility, subsidy, availability, and patient co-payment depend on the current listing and dispensing circumstances.

Australian regulatory classification is separate from our ordering policy. We do not require customers to upload or submit a prescription before we accept an order for Flagyl ER. This checkout policy does not change the medicine's Schedule 4 status or replace the need to use it only under a prescriber's direction. Suspected adverse effects can be reported to the Therapeutic Goods Administration, which monitors medicine safety in Australia.

Ordering, delivery, and receiving your order

Once you choose a strength and pack size, our checkout confirms the exact option selected before payment. We have supported Australian customers since 2010, and our support team is available 24/7 by email, online chat, or phone. A pharmacist is also available to answer questions about the product or your order.

Before completing checkout:

• confirm that the selected option says Flagyl ER and identifies an extended-release oral tablet;
• check that the strength is 200 mg or 400 mg as directed;
• review the tablet quantity and current total price;
• check the delivery address and postcode; and
• keep the order confirmation so the delivered pack can be checked against it.

Once your pack arrives:

• Store Flagyl ER at 20°C to 25°C in a tightly closed, light-resistant container and protect it from light.
• Check the expiry date printed on the pack against how long the prescribed supply is expected to last.
• Keep tablets in their original packaging unless a pharmacist provides different storage instructions.
• Keep the medicine out of the reach of children and do not use tablets that are damaged, discoloured, or past their expiry date.
• Contact our support team if a delivered pack looks damaged, incomplete, or different from the option selected at checkout.

Making a value-based decision

Choosing among our Flagyl ER options comes down to matching the exact extended-release product, prescribed strength, and appropriate quantity, then using the package comparison to assess the value of the relevant option. A lower price per tablet is useful when it aligns with a genuine treatment plan, suitable storage, and use before expiry, but it should not be the reason to buy more antibiotic tablets than needed.

Review the 400 mg comparison when that is the prescribed strength, check the separately displayed offer for 200 mg when applicable, and confirm every detail before payment. With the strength, pack size, and current price clearly identified in our checkout, you can place the order knowing which option will be packed and dispatched.